fix: when obtaining locks, use mode 666 on Linux by default.

Doing so helps with using `sudo` and others.

gix-lock/src/acquire.rs

@@ -60,6 +60,8 @@ impl File {
     /// If `boundary_directory` is given, non-existing directories will be created automatically and removed in the case of
     /// a rollback. Otherwise the containing directory is expected to exist, even though the resource doesn't have to.
     ///
+    /// Note that permissions will be set to `0o666`, which usually results in `0o644` after passing a default umask, on Unix systems.
+    ///
     /// ### Warning of potential resource leak
     ///
     /// Please note that the underlying file will remain if destructors don't run, as is the case when interrupting the application.
@@ -71,7 +73,11 @@ impl File {
         boundary_directory: Option<PathBuf>,
     ) -> Result<File, Error> {
         let (lock_path, handle) = lock_with_mode(at_path.as_ref(), mode, boundary_directory, &|p, d, c| {
-            gix_tempfile::writable_at(p, d, c)
+            if let Some(permissions) = default_permissions() {
+                gix_tempfile::writable_at_with_permissions(p, d, c, permissions)
+            } else {
+                gix_tempfile::writable_at(p, d, c)
+            }
         })?;
         Ok(File {
             inner: handle,
@@ -87,6 +93,8 @@ impl Marker {
     /// If `boundary_directory` is given, non-existing directories will be created automatically and removed in the case of
     /// a rollback.
     ///
+    /// Note that permissions will be set to `0o666`, which usually results in `0o644` after passing a default umask, on Unix systems.
+    ///
     /// ### Warning of potential resource leak
     ///
     /// Please note that the underlying file will remain if destructors don't run, as is the case when interrupting the application.
@@ -98,7 +106,11 @@ impl Marker {
         boundary_directory: Option<PathBuf>,
     ) -> Result<Marker, Error> {
         let (lock_path, handle) = lock_with_mode(at_path.as_ref(), mode, boundary_directory, &|p, d, c| {
-            gix_tempfile::mark_at(p, d, c)
+            if let Some(permissions) = default_permissions() {
+                gix_tempfile::mark_at_with_permissions(p, d, c, permissions)
+            } else {
+                gix_tempfile::mark_at(p, d, c)
+            }
         })?;
         Ok(Marker {
             created_from_file: false,
@@ -169,6 +181,18 @@ fn add_lock_suffix(resource_path: &Path) -> PathBuf {
     ))
 }
 
+fn default_permissions() -> Option<std::fs::Permissions> {
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::PermissionsExt;
+        Some(std::fs::Permissions::from_mode(0o666))
+    }
+    #[cfg(not(unix))]
+    {
+        None
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

gix-lock/tests/lock/file.rs

@@ -105,6 +105,16 @@ mod acquire {
         assert_eq!(file.lock_path(), resource_lock);
         assert_eq!(file.resource_path(), resource);
         assert!(resource_lock.is_file());
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            let perms = resource_lock.metadata()?.permissions();
+            assert_ne!(
+                perms.mode() & !0o170000,
+                0o600,
+                "mode is more permissive now, even after passing the umask"
+            );
+        }
         file.with_mut(|out| out.write_all(b"hello world"))?;
         assert_eq!(file.commit()?.0, resource, "returned and computed resource path match");
         assert_eq!(

gix-lock/tests/lock/marker.rs

@@ -71,6 +71,16 @@ mod commit {
         let dir = tempfile::tempdir()?;
         let resource = dir.path().join("the-resource");
         let mark = gix_lock::Marker::acquire_to_hold_resource(resource, Fail::Immediately, None)?;
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            let perms = mark.lock_path().metadata()?.permissions();
+            assert_ne!(
+                perms.mode() & !0o170000,
+                0o600,
+                "mode is more permissive now, even after passing the umask"
+            );
+        }
         let err = mark.commit().expect_err("should always fail");
         assert_eq!(err.error.kind(), std::io::ErrorKind::Other);
         assert_eq!(